Compact fluorescent lamps are widely used in residential and commercial applications. Their energy efficiency, compact size, high light output and relatively cool operation make them ideal replacements for both incandescent lamps and for bulky fluorescent lamps.
A fluorescent lamp has an illumination efficiency, in terms of light output, which is sensitive to the lowest temperature of the wall of the fluorescent tube. In particular, it is known that a fluorescent lamp operates with maximal illumination efficiency when the lowest temperature on the wall of a fluorescent tube, termed the cold spot, within a specific temperature range. This temperature range is understood to be between approximately 25.degree. C. and 55.degree. C., and if the minimum tube wall temperature is outside this range, the illumination efficiency decreases.
For reasons of safety and of esthetics, it is desirable often to employ a protective dome or globe over the illumination tube or tubes of a compact fluorescent lamp. Such a protective globe can be rigid and light-transmissive, and can protect the brittle illumination tubes from shock and breakage. The globe can also soften the illumination, e.g., by providing diffusion or prismatic reflection.
However, providing a protective globe on a fluorescent lamp can increase the operating temperature of the fluorescent tube or tubes therein, by restricting the heat-dissipation from each fluorescent tube. The resultant fluorescent tube operating temperature can then exceed the range for optimum illumination efficiency, which is undesirable.
U.S. Pat. No. 5,174,646 to Siminovitch et al. discloses a heat transfer structure for reducing the minimum wall temperature of a fluorescent tube, including when used with a protective enclosure. The disclosed heat transfer structure is in thermal contact with the fluorescent tube and removes heat from the tube wall by thermal conduction.
It is an object of this invention to provide a fluorescent lamp having a globe, or for use with a globe and which can dissipate sufficient heat to maintain the fluorescent tube operating at a temperature of high illumination efficiency. Another object of the invention is to provide a compact fluorescent lamp having a thermal dissipation element of the above character and which allows for ready installation and replacement of a fluorescent tube.
Further objects of the invention are to provide compact fluorescent lamp apparatus of the above character that can be manufactured and fabricated at relatively low cost and with an attractive appearance.
Other objects of the invention will in part be obvious and will in part appear hereinafter.